Inflammatory bowel disease (IBD) is a serious problem that reaches across the globe. If you’re one of the 5 million people worldwide who deals with IBD, you might be curious about the disease’s origins. How did conditions like ulcerative colitis (UC) and Crohn’s disease become so widespread, and why are they more prevalent in some groups of people than in others? Well, thanks to a new report, we are now getting a clearer understanding of this.

The review published in January 2018 in the World Journal of Gastroenterology examines the role race and global migration played in the development of IBD over time. It also shows the impact environmental factors, like the typical diet of a country, might have played on different groups’ susceptibilities to developing IBD as they migrated from one place to another.

The team, led by researchers at St. Mark’s Hospital and Academic Institute in London, analyzed data on South Asian migrants and found that compared with caucasians, people of South Asian descent had a higher incidence of UC than the local population.

“There are several observations that implicate environmental factors in the overall incidence of IBD,” says Naila Arebi, MD, PhD, lead author of the report, who is in the department of gastroenterology at St. Mark’s Hospital. According to Dr. Arebi, environmental factors that might lead to the development of IBD include:

Changes to the mother’s microbiome — the community of microorganisms that reside in all our bodies

Arebi says that for South Asian migrants, for example, these kinds of environmental factors really ramped up the predominance of UC, specifically. She adds that the prevailing belief is that these environmental factors could trigger certain genetic predispositions for IBD in people.

“For migrants, it may be related to a Westernized diet that changes the microbiome and, combined with a specific genetic factor, activates the disease,” she says. “(IBD) tends to present earlier in life in second generation migrants, compared with first generation, implying a lag phase of years.”

Garrett Lawlor, MD, assistant professor of medicine at the Columbia University Vagelos College of Physicians and Surgeons and associate director of Columbia’s inflammatory bowel program in New York City, who was not involved in the study, echoes these thoughts. Dr. Lawlor says this research mirrors past studies in how environmental triggers lead to chronic conditions.

“When a migrant develops the same risks for a disease as the country they have moved to, it suggests that something in the new environment may contain a trigger for the disease process,” he says. “That may be a particular form of infection, perhaps, change in food habits, or a combination of the two. Changes in food intake lead to subtle imbalances in the gut bacterial populations which may be the trigger for developing IBD. Because that would reflect a shift in many populations of bacteria rather than the introduction of one new bacteria, it can be more difficult to detect these casual changes. The data that we see here in IBD is an interesting picture that we have seen before. Previous similar studies have seen the same thing happen in celiac disease, where migrants increase their risk of being diagnosed from celiac disease based on where they go to live.”

A Future of Better Treatment for IBD

So, how could a clearer understanding of IBD’s origins help medical professionals treat the disease? Lawlor says this kind of research could provide doctors with a clearer window of understanding how IBD relates to the people they treat.

“The key to figuring out how to treat IBD is firstly to figure out what causes IBD,” says Lawlor. “We know it is a complex disease where gene mutations are required, a hyperactive immune system, and finally a trigger from the outside environment, such as a type of infection. Knowing this, scientists are learning how to calm down the immune system to allow healing to occur with the medications we use currently and in the future.”

Lawlor says that doctors are starting to see a future where gene mutations could potentially be altered to prevent IBD from occurring in the first place. Of course that future is still a ways off. He says that, right now, physicians are trying to identify the specific triggers that cause the disease and how people could avoid setting off those triggers.

Arebi adds that once researchers get a better handle on IBD’s causes, they could develop better drugs to fight inflammation from the disease.

The emphasis on the microbiome and IBD in this review has implications for other diseases as well. Lawlor says this kind of work fits in with other trends in how the microbiome may be part of the “development of many different diseases, including cancer” as well as how the microbiome affects the body’s ability to “use medications to help us heal.”

“The microbiome is an entire body system that we have had to ignore until recently because we simply didn’t have the scientific technology to assess it properly,” he says. “Exciting recent developments in this area of research continue to lead to new avenues of understanding, and future potential treatment targets. And an appropriate level of respect for the bugs living within our bodies.”